Correct Answer – C
`5e^(-)+MnO_(4)^(ө)rarrMn^(2+)`
`M^(x+)rarrMO_(3)^(ө)+(5-x)`
`x-6 = -1`
`x=5`
`”Equivalent of” MnO_(4)^(ө) = “Equivalent of” M^(x+)`
`1 mol xx 5= 1.67 mol xx (5-x)`
`:. X=2`

Correct Answer – 2
`Mn^(7+) + 5e rarr Mn^(2+)`
`:. 1` mole of `MnO_(4)^(-)` accepts `5` moles of electrons.
`:. 5` mole of electron are lost by `1.67` mole of `M^(x+)`
`:. 1` mole of `M^(x+)` will lose electron `= (5)/(165) ~~ 3` moles
Since `M^(x+)` change to `MO_(3)^(-)` (oxidation no. of `M = +5`) by accepting `3` electron
`:. x = +5 – 3=+2`

Correct Answer – A
`M^(x+)+MnO_(4)^(ɵ)toMO_(3)^(ɵ)+Mn^(2+)`
`MnO_(4)^(ɵ)+8H^(o+)+5e^(-)toMn^(2+)+4H_(2)O`
`M^(x+)+3H_(2)OtoMO_(3)^(ɵ)+6H^(o+)+(5-x)e^(-)`
`m” Eq of “MnO_(4)^(2-)-=m” Eq of “M^(x+)`
`1xx5-=[1.67xx(5-x)]implies5-x=3impliesx=2`